/Engine/Source/Runtime/UMG/Public/Blueprint/GameViewportSubsystem.h
Helper function to set the desired size in the viewport for the Slot.
static [FGameViewportWidgetSlot](API\Runtime\UMG\Blueprint\FGameViewportWidgetSlot) SetWidgetSlotDesiredSize ( [FGameViewportWidgetSlot](API\Runtime\UMG\Blueprint\FGameViewportWidgetSlot) Slot, FVector2D Size )